<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./../vue/vue@2.6.12.js"></script>
    <style>
        html,
        body {
            width: 100%;
            height: 100%;
        }

        #app {
            width: 100%;
            height: 100%;   
        }

        #top {
            border: 1px solid blue;
            height: 200px;
            width: 100%;
        }
    </style>
</head>
<body>
    <div id="app">
        <div id="top">
            1
        </div>
    </div>
</body>
</html>